This invention relates to monitoring gas turbine engines and, more particularly, to the monitoring and the operation of a surge bleed valve in a gas turbine engine and detecting a fault in the operation of such surge bleed valve.
Gas turbine engines, such as those used on jet engine powered aircraft, employ surge bleed valves for preventing compressor surge by bleeding or by-passing some of the airflow around one of the compressors. Unfortunately, such surge bleed valves sometimes fail to operate properly. For example, a surge bleed valve may stay open and fail to close after being instructed to close. This reduces the operating efficiency of the gas turbine engine.
A previously proposed method for detecting the failure of a surge bleed valve to open or close is to attach a position sensing switch to the surge bleed valve for providing a signal as to whether the valve is open or closed. There are, however, disadvantages to this approach. For one thing, the position sensing switch itself may malfunction and give a false indication of the surge bleed valve condition. Furthermore, the use of a position sensing switch complicates the construction of the surge bleed valve and increases its manufacturing cost.
As may be seen from the foregoing discussion, there is a need for a method of surge bleed valve fault detection which does not require the use of a position sensing switch.
In one aspect of the present invention, a method of detecting surge bleed valve faults in a gas turbine engine comprises monitoring an engine operating parameter in the gas turbine engine; transmitting a valve status change signal to a surge bleed valve in the gas turbine engine; and setting a valve operation check signal to a fault indicating state if the monitored engine operating parameter does not change by at least a predetermined amount immediately following transmission of the valve status change signal to the surge bleed valve.
These and other features, aspects and advantages of the present invention will become better understood with reference to the following drawings, description and claims.